Method and apparatus for image-based navigation

ABSTRACT

A system and method for a procedure that can be performed on an appropriate subject. A procedure may be planned, at least in part, prior to performing the procedure. An image may illustrate at least a portion of the planned procedure for confirmation and/or alteration of the planned procedure prior to performing the procedure.

FIELD

The subject disclosure relates to a system for planning and/orperforming a procedure, and exemplarily relates to a system to useimaging of a subject for planning and selecting a procedure for on asubject.

BACKGROUND

This section provides background information related to the presentdisclosure which is not necessarily prior art.

The images of a subject may be acquired prior to a procedure and intra-or post-operatively or post-procedurally. For example, image data can beacquired of a patient and a three-dimensional model of the subject canbe generated based upon the acquired image data. The three-dimensionalmodel can be used for various purposes, such as planning a procedure onthe subject including selecting an implant (if an implant is to bepositioned in the subject), determining entry points, and/ortrajectories for performing a procedure and/or implantation, and otherselected planning features. Further, the planning can includedetermining placement of a selected implant, such as a lead electrodefor a cardiac system (e.g., a cardiac synchronization system) or a leadfor a brain stimulation system.

SUMMARY

This section provides a general summary of the disclosure, and is not acomprehensive disclosure of its full scope or all of its features.

A system and/or method is/are disclosed that may be used to plan atrajectory and/or placement of an instrument. The planning may be forplacing an implant and/or positioning an instrument temporarily. Forexample, planning may include selecting a trajectory for placing a deepbrain stimulation (DBS) probe in a subject, positioning a fastenerwithin an enclosed structure of a subject, or other procedure.Similarly, planning may occur for performing a tumor biopsy, removal ofan obstruction, or the like.

Often, prior to a procedure, planning may be performed for theprocedure. The planning may include various steps, such as selecting anentry point, selecting a target, and selecting a trajectory to reach thetarget. The trajectory may generally include a direction and type ofmotion to move an instrument from the entry point to the target. Theentry point may include an area or volume within an entry portal orpassage through which the instrument may move, wherein the instrumentincludes a smaller dimension than the entire possible area of the entryportal. Therefore, an entry point may be smaller than an entry portal.

When planning a procedure, the user may review a map, including animage, of the subject prior to performing the procedure. The image ormap of the subject may illustrate locations of various features, such asa target for a procedure. Further, the map or image data may illustrateor be used to determine a possible entry point. In addition to featuresor portions of the subject that may be illustrated with the map, adisplay device may be used to illustrate limitations and boundariesrelevant to the selected procedure. For example, a guide instrument mayhave a size and range of motion to guide an instrument for a procedure.The extent of the range of motion may be illustrated on the image or mapto assist in planning, including finalizing or selecting, a trajectory,guide, and other portions of a procedure.

Further areas of applicability will become apparent from the descriptionprovided herein. The description and specific examples in this summaryare intended for purposes of illustration only and are not intended tolimit the scope of the present disclosure.

DRAWINGS

The drawings described herein are for illustrative purposes only ofselected embodiments and not all possible implementations, and are notintended to limit the scope of the present disclosure.

FIG. 1 is an environmental view of a plurality of systems that may bepresent in an operating theatre and/or used prior to a procedure,including an optional imaging system and a navigation system;

FIG. 2 is a first image based on image data acquired of a subject,according to various embodiments;

FIG. 3 is a second image based on image data acquired of a subject,according to various embodiments;

FIG. 4 is a is a first image based on image data acquired of a subject,according to various embodiments;

FIG. 5 is a screen shot of a display device illustrating various imagesand information regarding a plan for a procedure on the subject;

FIG. 6 is a flow chart of a illustrating a process for planning aprocedure; and

FIG. 7 is a screen shot of a display device illustrating various imagesand information regarding a plan for a procedure on the subject.

Corresponding reference numerals indicate corresponding parts throughoutthe several views of the drawings.

DETAILED DESCRIPTION

Example embodiments will now be described more fully with reference tothe accompanying drawings.

With initial reference to FIG. 1 , a suite or assembly of systems 20 maybe provided for a selected procedure. The systems may includeinstruments, processing systems, and the like may be included. Invarious embodiments, the suite 20 may include a navigation system 22that may include one or more tracking systems 24, such as an opticaltracking system including an optical localizer 26 and an electromagnetictracking system including an electromagnetic tracking localizer 28. Thetracking systems 24 may communicate with various instruments, asdiscussed herein, via a coil array controller/navigated instrumentinterface (CAC/NII) 30. The CAC/NII 30 may communicate with aworkstation or other processing system or assembly 34. The navigationprocessor system 34 may include a navigation processing unit 36 that isconfigured and operable to access one or more navigation memory systems38. The navigation memory system 38 may include a non-transitory memorythat may include various features or programs stored for variousprocedures, such as instructions for determining a position (includinglocation and orientation) of a tracked instrument, illustrating orsuper-imposing an icon on an image 40 that is displayed on a displaydevice 42, or other appropriate instructions or program features, asdiscussed further herein.

The suite 20 may further include an imaging system 50, as discussedfurther herein. The imaging system 50 may include an imaging processingunit 52 that is incorporated with the imaging system 50, such asincluded or housed within a cart 54 and/or may be accessed remotely fromthe imaging system 50. The imaging processing unit 52 may process imagedata and transmit it to the navigation processing unit 36 via atransmission system 56 including wireless, wired, physical memorytransfer, or the like. The image data acquired by the imaging system 50may be used to generate the image 40 illustrated on the display device42. It is understood that any appropriate imaging system may be includedas the imaging system 50. The imaging system 50, specificallyillustrated in FIG. 1 , may include the O-arm® imaging system sold byMedtronic, Inc., having a place of business in Louisville, Colorado, butmay also include or alternatively include other imaging systems such ascomputer tomography (CT) imaging systems, magnetic resonance imaging(MRI) systems, C-arm fluoroscopy imaging systems, etc.

Image data may be acquired with any appropriate imaging system and maybe used to generate the image 40 for display on the display device 42.It is understood that any appropriate type or number of images may begenerated to be displayed on the display device 42. For example, theimage 40 may include a plurality of images along with various softwarefeatures or buttons, as illustrated in FIG. 5 . The images may alsoinclude a plurality of separate or discreet images that may beindividually viewed or selectively viewed by a user 60.

In addition to or alternatively to the navigation system 34, a planningsystem 100 may be used to display and/or manipulate the image data, asdiscussed herein. The planning system 100 may be used to assist in orperform planning of a selected procedure, such as by displaying icons ona display device 102 that displays the images. The image data acquiredwith the selected imaging system 50 may be used to generate an image forviewing on a selected display device, such as the display device 40and/or 102. In various embodiments, the user 60 may use the image dataacquired with the imaging system 50 to generate or determine a planprior to performing any portion of a procedure, such as forming a burrhole, an instrument, removing an access panel from a non-living subject,or the like. It is understood that any access portal, such as anyappropriate craniotomy, may be used in a selected procedure, and a burrhole is merely exemplary. In various embodiments, the planning system100 may receive image data from the imaging device 50 for display on adisplay device, such as the monitor 102. The planning system 100 mayfurther include various user inputs, such as a keyboard 104 or otherappropriate user inputs such as a track pad, mouse, or the like.

The planning system 100 may further include a planning processor system106, similar to the processor system 36 discussed herein. Further, theplanning system 100 may include a planning memory 108 similar to thenavigation memory 38 discussed herein. The planning processor system 106of the planning system 100 may be able to execute various instructions,such as stored in the memory 108 to assist in planning a selectedprocedure on the subject 82. Further, the memory 108 may have writtenthereto a plan that is determined for performing the procedure. Asdiscussed herein, the planning system 100 may be used to determine aplan for performing a procedure. The plan may be made prior to aprocedure and may be stored to the memory 108. Thus, the plan may bepredetermined prior to performing the procedure.

In various embodiments, including a specific example discussed herein,an instrument 120 may be planned to be positioned into a cranium 124 ofthe subject 82. The instrument 120 may be positioned or guided into thesubject 82 through a selected guide system 128. The guide system 128 maybe positioned relative to the cranium 124 of the subject 82, such asfixed to the cranium 124 and surrounding or positioned within a burrhole formed in the cranium 124. The guide system 128 may includeselected or appropriate guide systems including those disclosed in U.S.Pat. Nos. 7,637,915; 8,301,226; or 7,695,480, all incorporated herein byreference. The guide system 128 may further include the Navigus® guidedevice and/or the Nexframe® guide device, both sold by MedtronicNavigation, Inc. having a place of business in Louisville, Colorado. Itis understood, however, that the guide system 128 may be any appropriateguide that may be used to guide any selected instrument, such as theinstrument 124 into the subject 82. The guide system 128 may includevarious guiding dimensions and geometries that may be selected or fixedby the guide that are predetermined and may be illustrated for planningand selecting a device, such as the guide 128 as discussed furtherherein.

Turning reference to FIG. 2 , FIG. 3 , FIG. 4 , and FIG. 5 , variousimage views are illustrated. It is understood that the image views, asdiscussed herein, may be viewed with the planning system 100 on thedisplay device 102, such as during planning prior to any procedureoccurring and/or with the navigation system 34 on the display device 42during a procedure. Thus, a predetermined or pre-planned plan may bemade and saved, such as in the memory 10, for recall at a later time.For example, the navigation system 34 may recall the pre-plan fordisplay on the display device 42. Also, the user 60 may alter thepre-plan during a procedure for various purposes (e.g. brain shift,further development of a disease state, etc.).

A first image view 80 is illustrated in FIG. 2 . The image view 80 maybe at a selected orientation relative to a subject 82. FIG. 3illustrates a second image 86 at a different or alternative perspectiverelative to the subject 82. FIG. 4 illustrates an image 90 at a thirdperspective relative to the subject 82 and may also be an instrument“eye-view”, such as along a long axis of the instrument. FIG. 5illustrates a screen shot where a view may include a plurality of viewsof the subject.

With continuing reference to FIGS. 2-5 , the user 60 may acquire imagedata of the subject 82 with a selected imaging system, such as theimaging system 50 illustrated in FIG. 1 , or any other appropriateimaging system. Image data may be acquired with various two-dimensionalimaging modalities such as a C-arm or other appropriate two-dimensionalx-ray imaging system, as discussed further herein. Further,three-dimensional image data may be acquired of the subject 82 usingvarious imaging modalities including magnetic resonance imaging (MRI),computed tomography (CT), or other imaging modalities. It is understood,however, that three-dimensional images may be reconstructed based on twoor more two-dimensional images. In addition, two-dimensional images maybe made based on three-dimension image data, as is understood by oneskilled in the art.

The images 80, 86, 90, and 40 may be used by the user 60, as discussedfurther herein, to plan a procedure on the subject 82. The planning ofthe procedure for the subject 82 may include various steps or portionsas illustrated in a process or flowchart 140, illustrated in FIG. 6 . Itis understood that the flowchart 140 may incorporate features orportions may be accessed and/or operated with either or both of thenavigation system 34 or the planning system 100. For example, the user60 may perform an entire planning procedure prior to entering anoperating room or without the patient 82 present, but may use either theplanning system 100 or the navigation system 34. Further, during aprocedure, the user 60 may plan various portions of the procedure, suchas selection of the guide 128 and/or placement of an access portal, andmay use only the navigation system 34 or the planning system 100. Thus,it is understood that the planning process, such as illustrated withinthe flowchart 140 may be performed with any appropriate system.

Further, various processes illustrated in the flowchart 140 areperformed by a processor, such as one or both of the processor 106and/or the processor 36 based upon inputs from the user 60 or otherappropriate user and executing instructions stored in a selected memory.Therefore, it is understood that various features of the flowchart 140may be formed as instructions or formulated as an algorithm that can beincorporated into instructions to perform various steps or features asdiscussed further herein.

The flowchart 140 may, therefore, start at a start block 142. A user,such as the user 60, may select a procedure. For example, a surgeon mayselect a brain tumor biopsy of the subject 82 in block 144. It isunderstood, however, that other appropriate procedures may also beselected such as implanting a deep brain stimulation (DBS) lead orprobe, inserting or assembling a selected construct, or the like. Once aprocedure is selected in block 144, however, the selected type ofprocedure may be input into the planning system 100 in block 146. It isunderstood that inputting the selected procedure in block 146 into theplanning system 100 may be optional; however, the planning system mayinclude instructions to assist in selecting types of data and selectinginstrumentation for performing a procedure. The input may include theuser 60 selecting from a menu a type of procedure, or selecting variousinstruments and guides for a procedure. It is understood, however, thatthe user 60 may also select various options such as the type of data toacquire, instrumentation to use, and the like.

Acquiring image data in block 150 may therefore be based upon an inputfrom the user 60, directly alone, or based upon a determination orautomatic selection by the planning system 100. The automatic selectionof the type of image data may be transmitted directly from the planningsystem 100 to the imaging system 50 with a transmission line 56′, asillustrated in FIG. 1 . The user 60, however, in determining orselecting the acquisition of image data in block 150 may also transmitinstructions to the imaging system 50, via the transmission line 56′.The user 60, however, may also communicate the type of image data to beacquired in any other appropriate manner, such as via oralcommunication, messaging, or the like to an operator of the imagingsystem 50. The image data of a point or portion of interest of thesubject 82 may then be acquired in block 150 with the imaging system 50for use in planning a procedure.

Selecting a device for the selected procedure may occur in block 152.The selection of the device may occur concurrently with, before, orafter the acquisition of image data in block 150. The placing of theselection of the device in block 152 to follow the acquisition of theimage data 150 is merely exemplary. However, the selection of the devicein block 152 may be used by the planning system 100 to assist inpreparing or finalizing a plan for performing a procedure on the subject82. The subject procedure in block 144 may use one or more instrumentsthat are positioned within the cranium 124 of the subject 82. Theselection of the device 152 may include the selection of the instrumentsto be positioned into the patient 82. Further, the selection of thedevice in block 152 may include the selection of more than one deviceand/or devices that will be used together. For example, one or moreguide devices 128 may be selected to assist in guiding the instrument120 into the patient 82. In addition, the selection may include a guideand an instrument to be guided by the guide.

The selected device(s), which may include the instrument 120 and theguide 128 and are used to assist in determining selected geometries,dimensions, and the like for using the instrument 120. Accordingly, theselection of the device in block 152 may be used by the planning system100, as discussed further herein, to assist in planning a procedure bydetermining appropriate or limitations on dimensions and movement of theinstrument 120 and/or the guide 128. The selected geometries or range ofmotion or reachability may include various shapes that are defined by arange of motion (e.g. multiple degrees of motion). Shapes may includespheres, cones, cubes, rhombus, etc. As discussed herein, a volume ofreachability may be determined and displayed, such as relative to animage, for viewing and further determination.

With continuing reference to FIG. 6 and FIGS. 2-5 , the planning system100 may be used to assist in selecting or confirming a trajectory for aprocedure. The flowchart 140 illustrates that after selecting the devicefor a selected procedure, a process that may be executed by the planningsystem 100 automatically or in combination with the user 60 is may beentered. A display device, such as the display device 102, may displaythe selected image in block 160. Displaying the selected image mayinclude any appropriate or any number of selected images, as illustratedin FIGS. 2-5 . The displayed image may be of an entire portion of asubject, such as an entire head 124 or may include a selected portionthereof, such as a medial superior portion of the cranium 124, asillustrated in FIG. 2 . The planning system 100 may then automaticallyor with an input may be made to select an initial entry point in block162. For example, the user 60 may use the user input 104 to select anentry point 166, as illustrated in FIG. 2 . Alternatively, the processor106 may execute instructions to determine an initial entry point 166,such as segmenting the image to determine a flat portion or a pointnearest a determined tumor, etc. The entry point 166 in the image 80 maybe any appropriate size, but may be represented by a selected one ormore pixel/voxels or sub-pixel/voxel portion. As discussed furtherherein, various other information may be illustrated and determinedrelative to the entry point 166.

A target may be selected in block 170 which may be illustrated with atarget icon 174 on the image 80. The selected target in block 170 may bea part or all of a selected region of the subject 82, such as within atumor for performing a biopsy. The selected target may also be basedupon various anatomical or other information. For example, an atlasimage may be registered to the image 80 and an anatomical, including afunctional portion, of the anatomy may be selected as the target inblock 170. Therefore, the selected target in block 170 may be visible tothe user 60 or invisible to the user 60, but selected based upondeterminations relative to whether information, such as with an atlas,visible anatomical features, or the like.

Once an initial entry point is selected in block 162 and a target isselected in block 170, a determined and/or displayed initial trajectoryfrom the initial entry point to the target may be made in block 178. Theinitial trajectory may also be illustrated as a trajectory icon 182superimposed on the image 80 with the display device 102. The trajectoryicon 182 may be illustrated in any appropriate manner, such as astraight line. The processor 106 may calculate and display a straightline between and/or through the entry point 166 and the target 174 fordisplay on the image 80. It is understood, however, that the trajectoryicon 182 may be determined to be a non-straight line and may include oneor more curves along the path from the entry point 166 to the target174. The trajectory icon 182 may also be assisted or determined in partby the user 60. For example, the user 60 may determine the target 174and draw or drag a ray or line from the target 174 to a point that maybecome the selected initial entry point of block 162. Nonetheless,according to various embodiments, the processor system 106 may executeinstructions calculating a line between points determined as theselected initial entry point in block 162 and a selected target in block170. The determination of the line may be made by determining oridentifying at least one pixel or voxel within an image for each of theentry points 166 and the target 174 and calculate a line between the twopoints.

Once the selection of the initial point entry point in block 162 ismade, an illustration of a device icon 192 representing the selecteddevice and/or access port may be made in block 188. The illustration ofthe device icon 192 may include illustrating at least a first line 194 aand second line 194 b that are parallel to one another on thetwo-dimensional image 80. Further, a third line 196, perpendicular toboth the first and second lines 194 a, 194 b, may be illustratedinterconnecting or between the two parallel lines 194 a, 194 b. The icon192 may be illustrated substantially after the determination of theinitial entry point 166 and/or at any other appropriate time such asafter determining the trajectory in block 178.

The device icon 192 may represent at least a portion of the selecteddevice, such as the guide 128. The parallel lines 194 a and 194 b mayrepresent the dimensions of a burr or access portal to access theinterior of the cranium 124 of the subject 82. The third line 196 mayillustrate the base of the guide 128 that will rest or be fixed to anouter surface 198 of the cranium 124 of the subject 82. The parallellines 194 a and 194 b in combination with the third line 196 illustratethe dimensions through which the instrument 120 may or must pass alongthe trajectory 182. As discussed further herein, these may be used indetermining whether the initial trajectory 182 is within a possibilityof a boundary of motion or guiding of the guide 128. The device (e.g. aguide) may be positioned at any appropriate point on the patient 82.Therefore, the device icon 192 may be moved on the display devicerelative to the image 80, thus the lines representing the device icon192 may move to illustrate the boundaries relative to the guide deviceicon 192 and the image 82.

After illustrating the device icon 192 in block 188, the device icon 192may be aligned with a surface 198 of the image 80 in block 200. Theprocessor 106 of the planning system 100 may attempt to identify asurface or position the line 196 tangent to a curve at the entry point166. The user 60, however, may also use the user input 104 to alter ormove the line 196 to position it at a point that is substantially flator aligned on the surface 198 of the image 80. By ensuring that the line196 is flat or in most contact with the surface 198, the true extent orpossible boundaries of trajectories may be known relative to the guide128.

The line 196, of the device icon 192, once aligned with the outersurface 198 of the image 80 may be used by the planning system 100 toidentify geometries or ranges of reachability or procedural limitsrelative to the line 196, which represents the guide 128. As discussedabove, the line 196 represents a surface of the guide 128 that will bepositioned on the skull 124 of the subject 82. Therefore, the line 196determines the selected geometry of the guide 128 and an extent ofpossible guiding of the instrument 120 within the subject 82.Accordingly, once the device icon 192 is aligned in block 200, a displayof boundaries of guiding or an area or volume of reachability may beillustrated. The area or volume of reachability may include or define aboundary of all trajectories possible to be guided with the guide 128and may be displayed in block 210. The user 60 may be able to determine,prior to performing a procedure, whether a planned trajectory ispossible, such as able to be guided by a guide device.

A boundary line or set of boundary lines 212 may be defined relative tothe line 196 of the device icon 192 and may include one or more boundarylines illustrated as icons superimposed on the image, such as a firstboundary line 212 a, a second boundary line 212 b, and a third boundaryline 212 c. The boundary 212 may also include a base 212 d that isillustrated. The base 212 d may be a distance 213 from the line 196 andthat may be measured along a line normal to the line 196. The boundaries212 may define an entire workable or reachable volume of the selecteddevice, such as all trajectories possible with a selected guide and/orinstrument selected in block 152. In various embodiments, this mayinclude a boundary that may be achieved by moving or adjusting theguide, such as a X or Y stage of the guide (e.g. the Nexframe® guidedevice and/or the guide device disclosed in U.S. Pat. Nos. 7,981,120 and8,911,452, both incorporated herein by reference). Thus, based uponinformation regarding the instrument selected and device selected,boundaries 212 may be determined and/or recalled regarding angle ofdeflection from a center line/line normal to the line 196 and a depthfrom the entry point 166.

The boundary lines 212 may be defined by a cone, such as a rightcircular cone, having an apex or vertex at the entry point 166 and abased a distance into the subject 82 represented in the image 80. Thebase 212 d may be a height of the cone 213 from the entry point 166. Theapex of the cone defined by the boundary lines, however, may be above orbelow the line 196 and/or the entry point 166. The boundary lines 212represent the cone having a selected angle relative to the height linethat is perpendicular to the line 196 of the icon 192. The angle may bedefined by various features such as geometry of the guide 128, theexterior dimensions of the burr hole, as defined by the parallel lines194 a, 194 b, size of the instrument 120, or other specific geometriesof features. As illustrate in FIG. 2 , the two boundary lines 212 a and212 b extend from a center of the line 196, such as defined by the entrypoint 166, out or toward the interior of the image 80. The boundarylines 212 do not contact ends of the parallel lines 194 a and 194 b.Therefore, the extent of the boundaries 212 a-212 c may be defined bythe guide 128 and/or the burr hole formed through the skull 214 of thesubject 82.

Although illustrated as a cone in the FIGS. 2-5 , it is understood thatthe reachable space may be represented and/or determined to be anyappropriate shape, geometry, and size. The area or volume ofreachability, therefore, may be defined as any appropriate shape, and acone or triangle is merely exemplary. For example, selected guides maybe movable in straight lines on a X and Y stage, thus a volume or areaof reachability may be a square or cube. Other guides may allow for morecomplex movements of an instrument, and the boundaries that illustratethe area of volume of reachability may be other appropriate shapes.Further, the reachability may generally be a volume. The volume may bedisplayed in a three-dimensional (3D) image (e.g. FIG. 5 ) orrepresented by several lines on a two-dimensional (2D) image (e.g. FIG.2 ). It is understood, however, that the boundaries may be limited to anarea and may be illustrated as such on relative images.

The boundary line 212 may be viewed by the user 60 and/or analyzed bythe planning system 100 to determine whether the initial trajectory iswithin the boundary lines 212. Therefore, the flowchart 140 and theplanning process 100 may include a query of determining whether theinitial trajectory is within the boundaries 212 in block 220. Asdiscussed above, the boundary 212 defines and illustrates alltrajectories that are possible with the selected device (e.g. guide) ata selected location and position of the device.

If the initial trajectory is not within the boundaries 212, a no path222 may be followed to determine alter or select a new trajectory, newentry point, and/or new device in block 224. Selected feedback may beprovided to the user 60, such as a display, sound, tactile, or otherfeedback to indicate that the initial trajectory 182 is not within theboundaries 212. Thus, the initial trajectory is not within the cone ofreachability of the guide 128 that is represented by the icon 192. Thefeedback may be provided to the user 60, directly, and/or as aninstruction to the planning system 100 to alter a parameter to generatea new trajectory, as discussed herein, including selecting a new entrypoint, moving a guide relative to the selected entry point, etc.

The trajectory 182, as discussed above and illustrated in FIG. 2 , maybe an initial trajectory from the selected initial entry point 166. Thetarget 174 may be within an area that may include possible alternativetarget locations, such as within a tumor. Therefore, the target may bealtered relative to the initial entry 166 and a new trajectory 182′ maybe determined. In addition, or alternative to altering the location ofthe target 174 to calculate the new trajectory 182′ a new or alternativeentry point 166′, different from the initial entry point 166, may bemade. Changing the initial entry 166 to the alternative entry point 166′may form the alternative or new trajectory 182′ to even the same target174. Also, the device icon may be changed to represent a new ordifferent device (such as a straight or an angled guide). Further, theicon 192 may be moved to represent moving the guide relative to theselected initial entry point 166, which, in turn, moves the boundaries212 as well. Thus, multiple changes may be made to determine a newtrajectory in block 224.

On the display 102, the device icon 192 in combination the boundarylines 212 may then be moved relative to the new entry point 166′ andillustrated relative to the new trajectory 182′. Accordingly, thetrajectory may be altered by selecting a target different than theinitial target 174 and maintaining the initial entry point 166,selecting the new entry point 166′ while maintaining a target, oraltering the shape of the trajectory 182. Regardless, if the initialtrajectory 182 is not within the boundary lines 212 the new trajectory182′ may be determined by block 224. A further query block may then beused to determine if the new trajectory 182′ is within the displayedboundaries in block 228.

If the new trajectory 182′ is not within the boundaries 212, a no path230 may be followed to determine a new trajectory and/or new entry pointin block 224. The same alterations, as discussed above, may be made todetermine a new trajectory and query whether the new trajectory isdisplayed within the boundaries of block 228 may again be determined.Accordingly, an iterative process may be entered to determine atrajectory that is within the boundaries 212 by varying the parameters,as discussed above, such as the entry point, target point, trajectoryshape, guide, etc.

After a new trajectory is determined in block 224 and the query ofwhether the new trajectory is within the displayed boundaries 212 inblock 228, is positive or yes determination is made, a yes path 232 maybe followed. Similarly, if the initial trajectory 182 is determined tobe within the boundaries 212 in block 220 a yes path 234 may also befollowed. Both yes paths 232, 234 may follow to display a reachabletrajectory in block 240. A reachable trajectory is a trajectory that iswithin the boundary lines 212 and may be displayed on the display device102 of the planning system 100. It is understood that a reachabletrajectory may be substantially within the boundary lines 212. Forexample, an error or tolerance of about 0.01 millimeters (mm) to about 3mm may be used. Thus, even if the trajectory is touching or extends pastthe boundary line by about 3 mm it may be determined to be a reachabletrajectory.

Once the determination is made of a reachable trajectory, as discussedabove, the reachable trajectory may be saved as a plan (i.e. apredetermined plan) by the planning system 100 and/or the user 60 in thememory 108 for a selected procedure. The planning system 100 may then beused as the navigation processor system 34 and/or the plan may betransferred to navigation processor system 34 for performing a guidedprocedure. Alternatively, or in addition thereto, it is understood thata guided procedure is not required to occur, but rather that theplanning system 100 may be used to plan a portion of the procedure thatmay occur without a navigation system.

The planning system 100 may be used to determine and plan the entrypoint 166 and the location of the guide 128 to ensure that thetrajectory 182 is within the boundaries 212 to reach the target 174. Anavigation system may not be required to ensure that the instrument 120reaches the target 174 once the reachable trajectory is determined basedon the entry point 166 relative to the geometry of the guide andreachability as defined by the boundary lines 212. For example, theguide 128 may be positioned on the subject 82 based upon the plannedposition of the device icon 192. The trajectory 182, including path anddistance, for moving the instrument 120 into the subject 82 may bemeasured without a tracking system, as is understood by one skilled inthe art. For example, a guide portion may be set at a selected angle anda length of the instrument 120 may be preset with a stop. Accordingly,the process 140 may end in block 250.

It is understood that the end block 250 is the end of the planningprocess and may be the beginning the procedure on the subject 82. Theplan including the position of the guide 128 based upon the position ofthe device icon 192 and the determined reachable trajectory 182 to reachthe target 174 may be the results and the output of the process 140. Theplanning system 100 may display the icons, as discussed above, on theimage 80, as illustrated herein and discussed above, including positionsfor forming the burr hole into the subject 82, a position for the guide128, and a trajectory 182 of the instrument 120. Therefore, the planningsystem 100 may output for viewing by the user 60 a selected displayincluding a display on the display device 102 and/or the display deviceof 42. The display may include the image 80 including the icon 192 andthe trajectory 182 superimposed thereon. Any additional or further formsof output may include specific location and instructions, the length ofthe instrument 120, and other physical outputs to be used by the user60.

Further, it is understood that the image may be displayed with an iconof any appropriate type. For example, with reference to FIG. 3 , theicon 192 may be displayed on a substantially posterior two-dimensionalimage 86 of the subject. With further reference to FIG. 4 , it isunderstood that the boundary lines 212 may be illustrated as a circle212′ and the line 196 may be illustrated as a circle 196′. As discussedabove, the boundaries 212 may represent a cone or an exterior of a coneand the circle 212′ may illustrate the base of the cone or a perimeterof a cross-section of the cone at the depth of the target 174. Thecircle 196′ may illustrate the line 196 which represents the guide 128.Again, the trajectory 186 may be illustrated as well from the entrypoint 166 to the target 174. Further, with reference to FIG. 5 , a threedimensional rendering image 260 may have a boundary 212″ illustrated asa three dimensional cone relative to the three dimensional renderingimage 260. The trajectory 186 may also be illustrated relative to thethree dimensional cone boundary 212″ illustrated relative to thesuperimposed on the three dimensional rendering 260. Accordingly, it isunderstood that the boundaries and/or the trajectory 186 may beillustrated in the various matters relative to different perspectivesand different dimensionalities of the image.

According to various embodiments, a navigated procedure may be selected.The plan saved in the memory 108 may be used with the navigation system36 to navigate and guide the instrument 124 into the subject. Asdiscussed herein, the instrument 124 may be tracked and may the positionof the guide 128. The position of the instrument 124 may be illustratedas an instrument icon relative to the reachable trajectory or plan iconon the display device 42.

Thus, returning reference to FIG. 1 , the suite 20 is illustrated thatincludes navigation system 22 that can be used for various procedures.The navigation system 22 can be used to track the location of an item,such as an implant or the instrument 124, relative to the subject 82. Itshould further be noted that the navigation system 22 may be used tonavigate any type of instrument, implant, or delivery system, including:guide wires, arthroscopic systems, orthopedic implants, spinal implants,DBS leads, cardiac pacing leads, ablation instruments, etc. Moreover,the instruments may be used to navigate or map any region of the body.The navigation system 10 and the various tracked items may be used inany appropriate procedure, such as one that is generally minimallyinvasive or an open procedure.

The navigation system 22 can interface with the imaging system 50 thatis used to acquire pre-operative, intra-operative, or post-operative, orreal-time image data of the patient 82. It will be understood by oneskilled in the art, any appropriate subject can be imaged and anyappropriate procedure may be performed relative to the subject. Thesubject may be a human patient and the procedure may be a surgicalprocedure, such as an implantation of a device (e.g. a screw, lead,etc.).

Exemplarily illustrated in FIG. 1 , the imaging system 50 comprises anO-arm® imaging device sold by Medtronic Navigation, Inc. having a placeof business in Louisville, Colorado, USA. The imaging device 50 may havea generally annular gantry housing 270 that encloses an image capturingportion 272. The image capturing portion 272 may include an x-ray sourceor emission portion 274 and an x-ray receiving or image receivingportion 276 located generally or as practically possible 180 degreesfrom each other within the gantry housing 270. In various embodiments,the x-ray source or emission portion 274 and the x-ray receiving orimage receiving portion 276 may be mounted on a rotor (not illustrated)relative to a track (not illustrated) within the generally annulargantry housing 270. The image capturing portion 272 can be operable torotate 360 degrees during image acquisition. The image capturing portion272 may rotate around a central point or axis, allowing image data ofthe patient 82 to be acquired from multiple directions or in multipleplanes. The imaging system 50 can include those disclosed in U.S. Pat.Nos. 7,188,998; 7,108,421; 7,106,825; 7,001,045; and 6,940,941; all ofwhich are incorporated herein by reference. The imaging system 50,however, may also include or be replaced with other imaging systemsincluding C-arm fluoroscopic imaging systems, computer tomography (CT)imaging systems, etc. which can also generate three-dimensional views ofthe patient 82.

The position of the image capturing portion 272 can be precisely knownrelative to any other portion of the imaging device 50. In addition, asdiscussed herein, the precise knowledge of the position of the imagecapturing portion 272 can be used in conjunction with the trackingsystem to determine the position of the image capturing portion 272 andthe image data relative to the subject, such as the patient 82, which istracked. For example a patient tracking device 280 may be placed on thepatient 82 to track the patient 82.

The tracking system 24 can include various portions that are associatedor included with the navigation system 22. The tracking system 24 canalso include a plurality of types of tracking systems including anoptical tracking system that includes an optical localizer 26 and/or anelectromagnetic (EM) tracking system that can include an EM localizer28. The optical localizer 26 may “view” or optically track trackableportions (tracking devices) with cameras. The EM localizer 28 maygenerate a field and a trackable portion (e.g. EM tracking device) maysense the field to determination a location relative to another trackingdevice in the field. Various tracking devices, including those discussedfurther herein, can be tracked with the tracking system 24 and theinformation can be used by the navigation system 22 to allow for adisplay of a position of an item. Briefly, tracking devices, such as apatient tracking device 280, an imaging device tracking device 282, andan instrument tracking device 284, allow selected portions of anoperating theater to be tracked relative to one another with theappropriate tracking system 24, including the optical localizer 26and/or the EM localizer 28.

It will be understood that any of the tracking devices 280, 282, 284 canbe optical or EM tracking devices, or both, depending upon the trackinglocalizer used to track the respective tracking devices. It will befurther understood that any appropriate tracking system can be used withthe navigation system 22. Alterative tracking systems can include radartracking systems, acoustic tracking systems, ultrasound trackingsystems, and the like.

An exemplarily EM tracking system can include the STEALTHSTATION®AXIEM™, STEALTHSTATION® S7™, or STEALTHSTATION® i7™ Navigation Systems,sold by Medtronic Navigation, Inc. having a place of business inLouisville, Colorado. Exemplary tracking systems are also disclosed inU.S. Pat. No. 8,644,907, issued Feb. 4, 23012, titled “Method AndApparatus For Surgical Navigation”; U.S. Pat. No. 7,751,865, titled“Method And Apparatus For Surgical Navigation”, issued Jul. 6, 2010;U.S. Pat. No. 5,913,820, titled “Position Location System,” issued Jun.22, 1999 and U.S. Pat. No. 5,592,939, titled “Method and System forNavigating a Catheter Probe,” issued Jan. 14, 1997, all incorporated byreference herein.

Further, for EM tracking systems it may be necessary to provideshielding or distortion compensation systems to shield or compensate fordistortions in the EM field generated by the EM localizer 28. Exemplaryshielding systems include those in U.S. Pat. No. 7,797,032, titled“Method and system for navigating a catheter probe in the presence offield-influencing objects”, issued on Sep. 14, 2010 and U.S. Pat. No.6,747,539, titled “Patient-shielding and coil system”, issued on Jun. 8,2004, all of which are incorporated herein by reference. Distortioncompensation systems can include those disclosed in U.S. Pat. No.6,636,757, titled “Method and apparatus for electromagnetic navigationof a surgical probe near a metal object”, issued on Oct. 21, 2003, allof which are incorporated herein by reference.

With an EM tracking system, the EM localizer 28 and the various trackingdevices can communicate through an EM controller within the CAC/NII 30.The EM controller can include various amplifiers, filters, electricalisolation, and other systems. The EM controller can also control thecoils of the localizer 28 to either emit or receive an EM field fortracking. A wireless communications channel, however, such as thatdisclosed in U.S. Pat. No. 6,474,341, entitled “Surgical CommunicationPower System,” issued Nov. 5, 2002, herein incorporated by reference,can be used as opposed to being coupled directly to the EM controller.

It will be understood that the tracking system may also be or includeany appropriate tracking system, including a STEALTHSTATION® TRIM®,TREON®, and/or S7™ Navigation System having an optical localizer,similar to the optical localizer 26, sold by Medtronic Navigation, Inc.having a place of business in Louisville, Colorado. Optical trackingsystems may also include those discloses in U.S. Pat. No. 8,010,177,Aug. 30, 2011, Intraoperative Image Registration”; U.S. Pat. No.6,235,038, issued on May 22, 2001, titled “System For Translation OfElectromagnetic And Optical Localization Systems”, all incorporatedherein by reference. Further alternative tracking systems are disclosedin U.S. Pat. No. 5,983,126, to Wittkampf et al. titled “CatheterLocation System and Method,” issued Nov. 9, 1999, which is herebyincorporated by reference. Other tracking systems include an acoustic,radiation, radar, etc. tracking or navigation systems.

The imaging system 50 can include the support housing or cart 54. Theimaging system 50 can further include the separate image processing unit52 that can be housed in the cart 54. The navigation system 22 caninclude the navigation processing unit 36 that can communicate orinclude a navigation memory 38. The navigation memory 38 may include anyappropriate non-transitory memory including a random access memory,magnetic media drive, etc. Further, the navigation memory 38 may beintegrated with the navigation processing unit 36 or remote from thenavigation processing unit 36. The navigation processing unit 36 canreceive information, including image data, from the imaging system 50,plan information from the planning system 100 (if planned separatelyfrom the navigation system 34), and tracking information from thetracking systems 24, including the respective tracking information fromthe tracking devices 280, 282, 284 and the localizers 26, 28. Image datacan be displayed as the image 40 on the display device 42 of theworkstation or other computer system 34. The workstation 34 can includeappropriate input devices, such as user input devices including akeyboard 290. It will be understood that other appropriate input devicescan be included, such as a mouse, a foot pedal or the like. The variousprocessing units and computers or workstations may include internal orlocal memory and processing units. The processing units may includecentral processing units that are general computers that executeinstructions to perform tasks on a chip. The processing units may alsobe specific circuits, such as application specific integrated circuits(ASIC). Accordingly, the processing units may be devices that receiveinformation and execute instructions that are stored or received basedon the information.

The image processing unit 52 may process image data from the imagingsystem 50 and transmits it to the navigation processing unit 36. It willbe further understood, however, that the imaging system 50 need notperform any image processing and it can transmit the image data directlyto the navigation processing unit 36. Accordingly, the navigation system22 may include or operate with a single or multiple processing centersor units that can access single or multiple memory systems based uponsystem design.

The patient 82 can be fixed onto an operating table 292, but is notrequired to be fixed to the table 292. The table 292 can include aplurality of straps 72944. The straps 294 can be secured around thepatient 82 to fix the patient 82 relative to the table 292. Variousapparatuses may be used to position the patient 82 in a static positionon the operating table 292. Examples of such patient positioning devicesare set forth in commonly assigned U.S. patent application Ser. No.10/405,068, published as U.S. Pat. App. Pub. No. 2004/0199072, entitled“An Integrated Electromagnetic Navigation And Patient PositioningDevice”, filed Apr. 1, 2003, which is hereby incorporated by reference.Other known apparatuses may include a Mayfield® clamp.

Also, the position (including three-dimensional location andorientation) of the patient 82 relative to the imaging system 50 can bedetermined by the navigation system 22 with the patient tracking device280 and the imaging system tracking device 282. As discussed herein, theposition (including three-dimensional location and orientation) relativeto the patient 82 may be determined, at least in part, with imagesacquired of the patient 82. Accordingly, the position (includingthree-dimensional location and orientation) of the patient 82 relativeto the imaging system 50 can be determined. The imaging system 50, suchas the O-arm® can know its position and be repositioned to the sameposition within about 10 microns. This allows for a substantiallyprecise placement of the imaging system 50 and precise determination ofthe position of the imaging device 50. Precise positioning of theimaging portion 272 is further described in U.S. Pat. Nos. 7,188,998;7,108,421; 7,106,825; 7,001,045; and 6,940,941; all of which areincorporated herein by reference. Generally, it may be selected todetermine the position of the image data relative to the patient 82. Forexample, the position, including the orientation relative to thepatient, of the image data may be used to determine a location of aportion of the patient 82.

Subject or patient space and image space can be registered byidentifying matching points or fiducial points in the patient space andrelated or identical points in the image space. The imaging device 50,such as the O-arm® imaging device sold by Medtronic, Inc., can be usedto generate image data at a precise and known position. This can allowimage data that is automatically or “inherently registered” to thepatient 82 upon acquisition of the image data. Essentially, the positionof the patient 82 is known precisely relative to the imaging system 50due to the accurate positioning of the imaging system 50 relative to thepatient 82. This allows points in the image data to be known relative topoints of the patient 82 because of the known precise location of theimaging system 82.

Alternatively, manual or automatic registration can occur by matchingfiducial points in image data with fiducial points on the patient 82.Registration of image space to patient space allows for the generationof a translation map between the patient space and the image space.According to various embodiments, registration can occur by determiningpoints that are substantially identical in the image space and thepatient space. The identical points can include anatomical fiducialpoints or implanted fiducial points. Exemplary registration techniquesare disclosed in Ser. No. 12/400,273, filed on Mar. 9, 2009, nowpublished U.S. Pat. App. Pub. No. 2010/0228117, incorporated herein byreference.

Once registered, the navigation system 22 with or without the imagingsystem 50, can be used to perform selected procedures. Accordingly, itis understood that the subject 82 need not be within the imaging system50 during a navigated procedure. The subject 82 may be away from theimaging system 50 but the instrument 120 may be tracked.

Selected procedures can use the image data generated or acquired withthe imaging system 50. Further, the imaging system 50 can be used toacquire image data at different times relative to a procedure. Asdiscussed herein, image data can be acquired of the patient 82subsequent to a selected portion of a procedure for various purposes,including confirmation of the portion of the procedure.

With continuing reference to FIG. 1 , the imaging system 50 can generateactual or virtual three dimensional images of the patient 82. Thepatient 82 can be placed relative to the imaging system 50 to allow theimaging system 50 to obtain image data of the patient 82. To generate 3Dimage data, the image data can be acquired from a plurality of views orpositions relative to the patient 82. The 3D image data of the patient82 can be used alone or with other information to assist in performing aprocedure on the patient 82 or an appropriate subject. It will beunderstood, however, that any appropriate imaging system can be used,including magnetic resonance imaging, computed tomography, fluoroscopy,etc. to acquire image data (including 3D image data) of the patient 82.

As discussed above, the user 60 may use the plan to perform theprocedure. With reference to the figures, including FIG. 1 and FIG. 5 ,the instrument 120 may be tracked. The tracking device 284 coupled tothe instrument 120 may include any appropriate tracking device, such asa reflector array viewable by the optical localizer 26 or an EM coiloperable with the EM localizer 28. Nevertheless, the position of aportion (such as a distal tip) of the instrument 120 may be tracked. Thetracked position may be illustrated as an instrument icon 300superimposed on the image 40 with the display device 42. the user 60 mayview the display device 42 and see the tracked position of theinstrument by viewing the instrument icon 300. The position of theinstrument 120 relative to the preplanned reachable trajectory 182 mayalso be viewed.

Initially, the formation of an entry portal at the entry point 166 maybe tracked by tracking the instrument to form the entry portal at theentry point may be tracked. As noted above, the entry portal may includeany appropriate portal, including selected craniotomies such as burrholes. The tracked position of the portal forming instrument may bedisplayed with the display device 42. Also, the position of the guide128 maybe tracked as it is positioned on the cranium 124. Also, theangle or position of the guide relative to the patient 82 may betracked.

In addition to or alternatively to, pre-planning the position of thedevice with the planning system 100, the panning system 100 and/or thenavigation system 32 may be used to determine, during a procedure, aposition for at least one of the device (e.g. guide 128) or the entrypoint. For example, the guide 128 may be tracked with a guide trackingdevice 310 (e.g. similar to the tracking devices discussed above) andthe position of the guide may be tracked with the tracking systems 24.Thus, the device icon 192 and the boundaries 212 may be displayed on thedisplay device 42, such as superimposed on the image 40. The user 60 maymove the guide 128 and the device icon 192 and the boundary lines 212may be moved on the display device 42 based on the tracked position ofthe guide 128. In this way, the guide 128 may be selectively positionedduring a procedure to ensure that the volume or area of reachability ofthe guide 128 will include the planned trajectory 182. The trajectory182 may be planned at any appropriate time as well, such as prior to orduring the procedure. The trajectory 182 may be displayed with thedisplay device 42 relative to the boundary lines 212.

When the guide 128 is tracked, the user 60 may view the display 42 todetermine that the boundaries 212 of the area or volume of reachabilityof the guide 128, or other appropriate device, overlaps or includes theplanned trajectory 182 when positioned near and/or on the patient 82,but prior to fixation to the subject 82. The boundaries 212 may includedimensions input by the user 60 and/or selected from a menu. The user 60may select the guide 128 from a menu and the processor 36 and/or 106 mayrecall the dimensions and geometry of the boundaries 212 from the memory38 and/or 108. Nevertheless, the device icon 192 and the boundaries 212may be displayed on the display device 42 based on the tracked positionof the guide 128 relative to the subject 82 with the tracking system 24.This may also allow the user 60 to alter (e.g. move within a burr hole)the position of the guide 128 from a pre-planned position, but stilldetermine and confirm that the planned trajectory 182 is within the areaor volume of reachability by viewing the display device 42 and thedevice icon 192 and/or the boundary 212.

As illustrated in FIG. 5 , the position of the reachable trajectory isknown by the preplanned position of the entry point 166 and the guide128 determined by the line 196 and/or based on the tracked position ofthe guide 128. Thus, the instrument icon 300 representing the trackedposition of the instrument 120 may be displayed relative to the otherpreplanned icons. In this way, the user 60 may determine and/or confirmthat the instrument 120 is on the preplanned reachable trajectory 182.The user 60 may also know when the instrument 120 reaches the target 174by viewing the instrument icon 300 relative to the target icon 174.

If the instrument 120 is tracked off of the preplanned trajectory,however, feedback may be provided to the user 60. For example, a visual,auditory, tactile, or other indication may be provided to the user 60that the instrument is not tracked on the preplanned trajectory 182.Thus, the plan may be used with a navigated procedure.

With continuing reference to FIG. 6 and additional of FIG. 7 , theflowchart of 140 may be used for selecting or confirming an appropriatedevice, such as the guide 128. As discussed above, various guides mayhave selected the limitations, and/or features. For example, a guide mayinclude a guide system that has two guide bodies, one with a straightguide portion and/or one with an angle guide portion, such as thestraight or angled Navigus® guide system sold by Medtronic Navigation,Inc. In a two part guide system, a straight guide may include a guidetube that is substantially perpendicular to a base affixed to thecranium 124. An angled guide, however, may include a tube angledrelative to a base that is fixed to the cranium 124. Therefore,different boundaries of an area or volume of reachability may beprovided or defined by the two different guide portions. Accordingly,with reference to FIG. 7 , an image 350, 352, 354, and 356 may bedisplayed on a display device, such as the display device 102.

As illustrated in the flowchart 140 an initial selection of a device,including a guide, may be in block 152. A display of boundaries for theselected device may be displayed in block 210, as illustrated in FIG. 7. The boundaries illustrated, however, may include a plurality ofboundaries or ranges based upon a selected set of guides. Thus, a set ofboundaries may be illustrated with one or more boundary iconsrepresenting different boundaries of possible trajectories. In variousembodiments, as discussed above, a guide system may include two guides,such as one with an angled tube relative to a base and one with a morestraight tube a relative base. The straight to guide may include anarrow or smaller boundary 316, which may be a cone shaped volumeincluding a first boundary line 360 a, a second boundary line 360 bextending to a base 360 c. The boundary 360 may be illustrated relativeto the trajectory 182. With reference to the image 350 in FIG. 7 , thetrajectory 182 is within the boundary 360. Further, the boundary 360 maybe similar to the cone shaped boundary, as discussed above, including aheight that defines a workable and reachable volume by a selectedinstrument and/or guide combination. The boundary may illustrate anyappropriate or selected shape boundary, also as discussed above.

It is understood, however, that the trajectory 182 may not be within theboundary 360. The alternative or second boundary 370 may include asecond boundary icon an illustration of a first boundary line 370 a, asecond boundary line 370 b, and a base 370 c. The second or outerboundary 370 may be a shape similar to the inner or smaller boundary 360or may be an alternative shape. As illustrated in FIG. 7 , the outerboundary 370 is also a cone shape and has an apex at the same positionas the inner or smaller boundary 360, generally at the entry 166 point.The user 60 may view the display device 102 to understand and determinewhether the trajectory 182 is within either or both of the boundaries360, 370. The boundaries 360, 370 may be defined by or define a volumeor area that is reachable by the instrument 124 that is selected inblock 152 and/or 224. Further, the boundary 370 may be similar to thecone shaped boundary, as discussed above, including a height thatdefines a workable and reachable volume by a selected instrument and/orguide combination. The boundary may illustrate any appropriate orselected shape boundary, also as discussed above.

The user 60 may determine which of the two trajectory portions (e.g.straight or angled) is necessary or selected to include an area orvolume of reachability that includes the trajectory 182. Accordingly,rather than altering or selecting a different entry point of trajectory,the user 60 may select an appropriate guide device to achieve theselected trajectory 182. Further, the boundaries 360 and 370 illustratea workable or reachable volume in addition to angle of deflectionboundaries relative to a line normal to the line 196 and the entry point166.

In addition, the boundary 370 may illustrate all possible or an expanseof possible boundaries of the guide device depending upon a selectedposition of the guide 128 and/or movement of the guide 128. As discussedabove, the outer or larger boundary 370 may be based upon an angleguide. Therefore, being able to reach a selected portion of the outerboundary 370 may require a selected rotation or positioning of the angleguide relative to the subject 82. In other words, to reach the target174, even if within all possible boundaries 370, may require a specificpositioning of the guide 128 relative to the subject 82. Accordingly, asdiscussed above, the guide 128 may include the tracking device 310 ormay have a trackable instrument (e.g. a probe) that is positionable in aportion of the guide (such as an angled guide tube) when positioning theguide on the cranium 124. The boundary 370 may be illustrated on thedisplay device 102 and/or the display device 42 based upon a trackedposition of the guide 128 to insure that the guide 128 is positionedthat the boundary 370 encompasses the determined trajectory 182.

A rotational position may also be determined and illustrated in theplanning screen such as the rotational demarcation 380. For example, anindication of Rotation: Anterior may provide an indication that theangle guide must be angled towards the anterior of the subject 82 toallow for the boundary 370 to encompass or include the determinedtrajectory 182. Other indications may be made or determined anddisplayed for the user 60 to allow for a determination and confirmationthat the trajectory 182 is within the boundary 370.

With continuing reference to FIG. 7 , the display device 102 and/orrepresented by display device 34 may also include various differentviews and images that include illustration of the boundaries. Forexample, the image 353 may also illustrate the boundary 370 and 360relative to the trajectory 182 and the target 174. The image 352 may berotated 90 degrees relative to the image 350 or any other rotationalrelative to the image 350. Further, an instrument may show the boundary360 and 370 at a plane of the target 174 to allow the user 60 to viewthe trajectory along the path of the instrument 126 relative to theboundaries 360 and 370. Further, an image 356 may include a threedimensional display including a three dimensional boundary display 370′and a three dimensional boundary display 360′. Both three-dimensionalboundaries 360′, 370′ may be illustrated relative to the determinedtrajectory 182, at a plane of the target 174, and the entry 116.

Accordingly, it is understood that the boundary may be illustrated onvarious images that are acquired in block 150. The displayed boundariesin block 210 may include the boundaries as illustrated in FIGS. 2-5and/or as illustrated in FIG. 7 . The boundaries may include a singleboundary for a selected guide device or may include a plurality ofboundaries for a set of guides or more than one guide. The user 60 maythen determine whether the trajectory 182 is within the boundariesdisplayed in block 210 or alter or change at least one of thetrajectory, entry point, and/or device position and/or device in block234. Therefore, the flowchart 140 allows for determining, confirming,and/or selecting entry points, trajectories, and targets so that theinstrument 126 may be guided on the determined trajectory 182 to thetarget 174.

The foregoing description of the embodiments has been provided forpurposes of illustration and description. It is not intended to beexhaustive or to limit the invention. Individual elements or features ofa particular embodiment are generally not limited to that particularembodiment, but, where applicable, are interchangeable and can be usedin a selected embodiment, even if not specifically shown or described.The same may also be varied in many ways. Such variations are not to beregarded as a departure from the invention, and all such modificationsare intended to be included within the scope of the invention.

What is claimed is:
 1. A method of planning a procedure, comprising:displaying an image of a subject; superimposing a trajectory iconincluding at least a line representing a planned trajectory from aselected entry point to a selected target on the image; superimposing afirst and second device icon representing a first and second device atthe selected entry point on the image after superimposing the trajectoryicon on the image; and superimposing simultaneously both a selectedfirst boundary icon relating to the first device and a second boundaryicon relating to the second device extending from the superimposeddevice icon on the image after the device icon and the trajectory iconare both superimposed on the image, wherein the first boundary icon isconfigured to illustrate first boundaries of reachability and the secondboundary icon is configured to illustrate second boundaries ofreachability; tracking a position of the device such that the positionof the device icon and the selected first boundary icon and the secondboundary icon change relative to the displayed image when the device ismoved; providing feedback to a user that the trajectory icon is outsideof the selected first boundary icon or the second boundary icon; whereinthe trajectory icon is viewable relative to and with the superimposedfirst boundary icon and the second boundary icon to represent whetherthe planned trajectory is reachable with an intervention device that isseparate from and operable to be delivered through the device along anintervention device trajectory that is represented by the trajectoryicon.
 2. The method of claim 1, further comprising: moving at least oneof the first and second device icon so that a line at least one of thefirst and second device icon is substantially aligned on an exteriorsurface in the image.
 3. The method of claim 2, wherein the first andsecond device icon is superimposed including the line and a pair ofparallel lines; wherein the pair of parallel lines are bothperpendicular to the line.
 4. The method of claim 1, further comprising:selecting an alternative device; superimposing an alternative deviceicon on the image, different than the first and second device icon, thatrepresents the selected alternative device; and superimposing analternative boundary icon different from the other first boundary iconor second boundary icon.
 5. The method of claim 1, further comprising:determining a new entry point different from the initial entry point ifthe trajectory icon intersects the first or the second boundary icon;and superimposing a new trajectory icon from the determined new entrypoint.
 6. The method of claim 5, further comprising: determining a newtarget if the trajectory icon intersects the first or the secondboundary icon; and superimposing a new trajectory icon from thedetermined new entry point.
 7. A system for planning a procedure,comprising: a memory system configured to store a device icon, whereinthe device icon represents a device and is configured to illustrateboundaries of reachability with an intervention device separate from andwhen passed through the device; a processor system configured to executeinstructions to: access image data, instruct a display device to displayan image based on the image data, receive input from a user input deviceto instruct the display device to display a trajectory icon, configuredto represent a trajectory of the intervention device through the deviceas a line from an entry point to a target point superimposed on thedisplayed image, and receive input from the user input device toinstruct the display device to superimpose the device icon and a passageicon superimposed on the displayed image at a selected initial entrypoint after displaying the trajectory icon superimposed on the displayedimage, wherein the memory system configured to store the device iconincludes a first device icon and a second device icon, wherein the firstdevice icon is configured to illustrate first boundaries of reachabilityof a first device and the second device icon is configured to illustratesecond boundaries of reachability of a second device, wherein thedisplay device is configured to display the device icon as at least oneof a two-dimension icon or a three-dimension icon and wherein the deviceicon extends from the selected initial entry point toward the targetpoint to simultaneously illustrate the first and second boundaries ofreachability; track a position of the intervention device such that theposition of the trajectory icon and the device icon with the illustratedfirst and second boundaries of reachability change relative to thedisplayed image when the intervention device is moved; provide afeedback to a user when the trajectory icon is outside of the deviceicon based on the tracked position of the intervention device; wherein auser is able to view the display device to view the trajectory iconrelative to a selected one of the first device icon and the seconddevice icon and the passage icon to determine whether the trajectory isreachable with the intervention device through the device.
 8. The systemof claim 7, wherein the user input device is configured to be engaged bythe user to move the device icon so that a line of the device icon issubstantially adjacent an exterior surface in the image.
 9. The systemof claim 8, wherein the device icon includes the line and a pair ofparallel lines; wherein the pair of parallel lines are spaced apart andboth perpendicular to the line.
 10. The system of claim 7, furthercomprising: wherein the user input device is configured to allow theuser to select an alternative device.
 11. The system of claim 7, furthercomprising: wherein the processor system is configured to receive inputfrom the user input device to select a new entry point different fromthe initial entry point if the trajectory icon intersects a boundary ofthe boundaries of reachability of the device; wherein the processorsystem is configured to illustrate the device icon to illustrateboundaries of reachability with the intervention device separate fromand when passed through the device at the new entry point.
 12. A methodof at least one of planning or confirming at least a portion of aplanned procedure on a subject with image data acquired with an imagingdevice, comprising: accessing the image data of the subject, wherein theimage data is acquired with the imaging device; simultaneouslydisplaying superimposed on an image of the subject generated with theimage data: (i) a selected trajectory icon representing a plannedtrajectory including a line from a determined planned entry point intothe subject to a target within the subject for an interventioninstrument; (ii) a set of boundary icons, wherein the set of boundaryicons includes a first boundary icon representing a first boundary ofpossible trajectories achievable with the intervention instrument with afirst guide member at the determined planned entry point and a secondboundary icon representing a second boundary of possible trajectoriesachievable with the intervention instrument with a second guide memberat the determined planned entry point; (iii) a device icon representinga device at the determined planned entry point on the image; tracking aposition of the device such that the position of the device icon and theset of boundary icons change relative to the displayed image based onthe tracked position of the device; in response to determining theplanned trajectory is not within the first or second boundaries,providing visual feedback to indicate that the trajectory is not withinthe boundaries; and wherein the displayed superimposed selectedtrajectory icon relative to the superimposed set of boundary icons isoperable to be viewed and to determine whether the selected plannedentry point or the first or second guide member are possible to achievethe planned trajectory; wherein both the first boundary icon and thesecond boundary icon extend from the planned entry point toward thetarget.
 13. The method of claim 12, wherein the set of boundary iconsincludes a third boundary of possible trajectories achievable with athird guide member on the image at the planned entry point.
 14. Themethod of claim 12, wherein the first boundary icon is within the secondboundary icon.
 15. The method of claim 12, further comprising:evaluating whether the selected trajectory icon is within the firstboundary icon; if the selected trajectory icon is not within the firstboundary icon, then displaying the second boundary icon.
 16. The methodof claim 1, further comprising: wherein displaying the image includes atleast displaying a first image and a second image, wherein the firstimage is at a different perspective relative to the entry point and thetarget point than the second image; determining at least one of a newentry point, a new guide member, a new target point, or combinationsthereof when the displayed selected trajectory icon is not within thesuperimposed boundary icon; displaying at least one of a new trajectoryicon based on the new entry point, a new guide icon based on the newguide member, a new target point, or combinations thereof.